Answers (10)

So many reasons
Many have been told that for medical reasons they must begin to move their bodies, many see other people's successes and are inspired
Getting fed up with being tired.
Some people just need to come to terms with their BMI, waist measurements or weight and that's enough to get them to exercise.
I am still amazed that with all of the research that shows the positive benefits of exercise, we still have a generally sedentary/obese society.

For some it is intrinsic. They are natural movers. They enjoy movement. For others it is extrinsic. They do it because they were told to do so my someone or the individual might be preparing for a wedding or a big race or they feel they can get some type of benefit from it.

Whatever the reason one must have a compelling reason for staying fit.

Different things. Some are motivated by feelings that are vain, others are motivated by feelings of disgust or hatred of ones appearance, others are motivated by a life threatening diagnosis, event or story from a loved one, others for basic health reasons such as aches and pains or obesity... The list goes on and on.

as the others have stated, the list of reasons is long. But it can also change.

I remember a club member who started exercising after a cardiac event because he 'had to'. When I first met him, he had become a fixture because he was there almost every day. He told me: "That heart attack was the best thing that ever happened to me. Because of it, I started exercising, and I now feel better than at any point in my life before."

I wished there were more people like him ......
Karin Singleton
www.meltnc.com

In addtion to the excellent responses, I would only add two things. One is that in order for whatever modality to become part of an individual's lifestyle, it has to be an activity that's looked forward as enjoyable, not as a drudge.
Second is that the type(s), intensity, duration and frequency don't lead to pain or injury.

this is a very vague question but here are some... fear, pride, ego, endorphins, necessity...there are too many to list them all.

I personally train because I love the feel of heavy iron on my back...guess thats ego huh lol. I also train out of necessity because if I don't train my back will prevent me from being able to enjoy my 2 year old daughter.

There are as many reasons as people training out there. Few of those are:

Goal oriented
Necessity
Peer pressure
Family
Participation in a race or other athletic events
Curiosity (try different types of training styles)
Health issues (obesity, etc.)
The feeling they(military personnel, police officers and firefighters, etc.)
The feeling of belonging to a particular group (such as the Crossfit community)